Many products, such as paper, film, foil, textile, sheet metal, rope, yarn and wire are wound on rolls, coils, reels or spools which weigh from 50 to 10,000 pounds. Many cannot be lifted or maneuvered manually and require the intervention of some type of powered lifting apparatus.
A number of power lifting devices and related structures are known. See, for example, U.S. Pat. Nos. 3,263,938, 3,391,876, 3,423,120, 3,445,076, 3,734,328, 3,758,144 and 4,154,470, all of which issued to Herbert F. Dalglish.
A problem often encountered with the lifting and maneuvering of such heavy rolls of material is the transfer from the lifting apparatus to the shaft of a coil winding/unwinding machine. Typically, such a machine includes a rotatable shaft that is horizontally disposed and supported in cantilever fashion. The roll is maneuvered by the lifting apparatus so that its axis is horizontally disposed, and the lifting apparatus is thereafter brought to the winding/unwinding machine with the center probe of the lifting apparatus and the shaft of the machine in coaxial alignment.
Assuming that the operator can maintain the lifting apparatus in this aligned position, the roll is then physically transferred from the lifting apparatus to the shaft by physical strength. If the roll is particularly heavy, more than one operator may be necessary to push the roll from the lifting apparatus to the machine shaft. This task is not only difficult because of the size and weight of the rolls, but it is also difficult and dangerous. Alignment of the machine shaft with the center probe is easily lost, and if the lifting apparatus is supported from a single point on an overhead crane, continued registration is particularly difficult. Further, even when the center probe and machine shaft are aligned, it is possible for the roll to be dropped from its elevated position during the transfer process, and this is always dangerous to the operator or operators involved.